import java.util.Scanner;

public class HJ37 {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextInt()){
            int monthCount = sc.nextInt();
            System.out.println(fun(monthCount));
        }
    }

    public static int fun(int n)
    {
        if(n == 1 || n == 2){
            return 1;
        }else {
            return fun(n - 1) + fun(n - 2);
        }
    }
}
